If the probability for $$A$$ to fail in an examination is $$0.2$$ and that for $$B$$ is $$0.3$$, then the probability that either $$A$$ or $$B$$ fails is $$0.5$$

If the letters of the word "Assassin" are written down at random in a row, the probability that no two S's occur together is $$1/35$$